Sensor-machine interface and method for operating the same

ABSTRACT

The invention relates to a sensor-machine interface ( 1 ) for coupling at least one sensor ( 9 ) to at least one machine ( 10 ). Said interface comprises at least one sensor input ( 5 ) for receiving signals relating to the condition of the sensor, at least one machine output ( 8 ) for emitting signals that control the machine, a program memory ( 4 ), in addition to a control unit ( 3 ) for impinging the machine output in a program-controlled manner in accordance with the signals received via the sensor input. The invention also relates to a method for operating an interface of this type.

The invention relates to a sensor/machine interface for the coupling ofat least one sensor to at least one machine.

In accordance with the prior art, sensors such as light grids, lightbarriers or scanners are directly connected to a machine, for example toa press, to a robot, to an engine, etc. or to the control computerassociated with the machine.

Such a connection is disadvantageous when safety standards have to beobserved with respect to the total sensor/machine arrangement in orderto avoid injuries to operators, for example. In this case, thesafety-relevant job of evaluating signals coming from the sensor and oftransforming them into control signals or switch-off signals for themachine namely falls to the control computer associated with themachine. Accordingly, the whole control computer, which is relativelycomplex as a rule, must satisfy the respectively required safetystandards, although only a few of the jobs it has to do are relevant tosafety. Accordingly, even though it largely takes over jobs not relevantto safety, the complete control computer must therefore be designed suchthat it, and equally the software running on the control computer,satisfies the respectively applicable safety standards, which isassociated with a disadvantageously high economic effort. Thesatisfaction of the safety standards must in particular be inspected forevery machine or for every control computer, including the associatedsoftware, by a correspondingly responsible licensing office, whichadditionally increases the effort to be made.

An object underlying the invention consists of designing asensor/machine coupling of the said kind such that it can be realized atfavorable cost and such that it in particular simultaneously satisfiesthe respectively applicable safety standard.

In accordance with the invention, this object is satisfied by asensor/machine interface for the coupling of at least one sensor to atleast one machine having at least one sensor input for the reception ofsensor state signals, at least one machine out-put for the transmissionof machine control signals, a program memory and a control unit foroutputting program control signals to the machine output in dependenceon the signals received via the sensor input.

In accordance with the invention, the safety-relevant part of thecontrol computer belonging to a machine is therefore taken out of thecontrol computer and transposed into a sensor/machine interface. This isa separate, comparatively small assembly which is interposed between thesensor and the machine or between the sensor and the control computer ofthe machine. This assembly takes over the job of converting the signalscoming from the sensor into control signals or switch-off signals forthe machine. This advantageously has the effect that only thesensor/machine interface which is provided in accordance with theinvention and which is substantially less complex in comparison with themachine control computer has to satisfy the respectively applicablesafety standards, whereas the control computer can thus be designed at afavorable cost in a conventional manner. In addition, the sensor/machineinterface in accordance with the invention can be made such that it issuitable for connection to a plurality of different machines and to aplurality of different sensors such that in each case only one and thesame sensor/machine interface with the associated software has to belicensed with respect to the satisfaction of the applicable safetystandards for a corresponding plurality of different combinations ofsensors and machines. This brings about a further cost advantage.

The sensor/machine interface in accordance with the invention, which ispreferably accommodated in a housing separate from the sensor and fromthe machine, can additionally advantageously have at least one machineinput for the reception of machine state signals, with it being possibleto control the machine output by the signals received via the sensorinput and/or via the machine input. It accordingly becomes possible bythe said machine input to control a machine not only in dependence onsensor signals, but simultaneously also in dependence on machine states.

In a generalized form, the interface in accordance with the invention istherefore preferably operated such that, on the reception of specificsensor signals or machine state signals or of specific combinations ofsensor signals and machine state signals, no machine switch-off signalis transmitted and, on the reception of other sensor signals or machinestate signals via the machine output, a machine switch-off signal istransmitted.

It is furthermore of advantage for the machine output to be designed forthe transmission of machine switch-off signals and/or for thetransmission of machine actuation signals, in particular machine clocksignals.

The hardware and software of the sensor/machine interface in accordancewith the invention preferably satisfy customary safety standards, inparticular the standards IEC61508 and/or EN61496. To ensure these safetystandards, at least the control unit present in the interface can bepresent in duplicate in a redundant manner.

Different programs or program modules can be stored in the programmemory so that the program control of the machine output can be carriedout in different manners. The sensor/machine interface in accordancewith the invention can be matched to different operating demands, todifferent sensors and to different machines by this measure. Thedifferent programs or program modules can be loaded into the programmemory by an external programming device, in particular by a computer orby a laptop, via a programming interface. It is in particular possibleto assemble the programs stored in the program memory frompre-determined program modules via an operating interface in particularrunning on the computer or on the laptop. The assembly of the programsfrom individual program modules has the advantage that only theindividual program modules have to be inspected or licensed with respectto the satisfaction of safety demands, whereby it is then ensured thatthe programs assembled from these program modules also satisfy thecorresponding safety standards. A separate licensing of the finishedprograms is then no longer necessary so that—by the licensing of alimited number of program modules—a very much higher number of programsassembled from these modules is available without these programs havingto be separately licensed.

The sensor/machine interface in accordance with the invention can beprovided with a plurality of sensor inputs, sensor outputs, machineoutputs and/or machine inputs in order thus to permit the simultaneousoperation of a plurality of sensors and/or machines in connection with asingle sensor/machine interface.

Further preferred embodiments of the interface in accordance with theinvention and of methods for its operation are recited in the dependentclaims.

The invention will be described in the following with reference to anembodiment and to the only drawing. This drawing shows a block diagramof a sensor/machine interface with devices or machines connectedthereto.

The sensor/machine interface 1 in accordance with the invention isaccommodated in a housing 2. It has a control unit 3 which communicateswith a program memory 4.

The control unit 3 is furthermore in a position to receive signals whichare made available from a sensor input 5 and from a machine input 6. Thecontrol unit 3 can furthermore control a sensor output 7 and a machineoutput 8.

The sensor/machine interface 1 is connected to a sensor 9, for exampleto a light grid, via the sensor input 5 and the sensor output 7. Thesensor/machine interface 1 is connected to a processing machine 10, forexample to a press, in a corresponding manner via the machine input 6and via the machine output 8.

A program module memory 11 is furthermore present in the housing 2 and aplurality of program modules forming a program library are storedtherein. The program module memory 11 communicates like the programmemory 4 with the control unit 3.

The sensor/machine interface 1 is furthermore provided with aprogramming interface 12 to which a laptop 13 can be connected. Thelaptop 13 can communicate with the control unit 3 via this programminginterface 12.

The putting into operation of an arrangement in accordance with thedescribed block diagram can take place as follows, for example:

A laptop 13 is connected to the programming interface 12. Differentprogram modules are then loaded from the program module memory 11 viathe operating interface running on the laptop 13 and are assembled toone or more programs which are matched to the respective application andwhich are then stored in the program memory 4.

The unit of sensor/machine interface 1, sensor 9 and machine 10 cansubsequently enter into operation. The respective program running in thecontrol unit 3 can control the machine 10 in the desired manner via themachine output 8 in dependence on sensor state signals which aresupplied via the sensor input 5 and on machine state signals which aresupplied via the machine input 6.

1. A sensor/machine interface (1) for the coupling of at least onesensor (9) to at least one machine (10) having at least one sensor input(5) for the reception of sensor state signals, at least one machineoutput (8) for the transmission of machine control signals, a programmemory (4) and a control unit (3) for outputting program control signalsto the machine output (8) in dependence on the signals received via thesensor input (5).
 2. A sensor/machine interface in accordance with claim1, characterized in that the sensor/machine interface (1) isaccommodated in a housing (2) separate from the sensor (9) and from themachine (10).
 3. A sensor/machine interface in accordance with claim 1,characterized in that at least one machine input (6) is provided for thereception of machine state signals (8), with it being possible tocontrol the machine output in dependence on signals received via thesensor input (5) and/or via the machine input (6).
 4. A sensor/machineinterface in accordance with claim 1, characterized in that the machineoutput (8) is designed for the transmission of machine switch-offsignals and/or for the transmission of machine actuation signals, inparticular machine clock signals.
 5. A sensor/machine interface inaccordance with claim 1, characterized in that the hardware and thesoftware satisfy customary safety standards, in particular the standardsIEC61508 and/or EN
 61496. 6. A sensor/machine interface in accordancewith claim 1, characterized in that at least the control unit (3) ispresent in duplicate in a redundant manner.
 7. A sensor/machineinterface in accordance with claim 1, characterized in that differentprograms or program modules can be stored in the program memory (4) sothat the program control of the machine output (8) can be carried out indifferent manners.
 8. A sensor/machine interface in accordance withclaim 7, characterized in that the different programs or program modulescan be loaded into the program memory (4) by an external programmingdevice (13), in particular by a computer or by a laptop, via aprogramming interface (12).
 9. A sensor/machine interface in accordancewith claim 7, characterized in that a plurality of program modulesforming a program library can be assembled into programs.
 10. Asensor/machine interface in accordance with claim 7, characterized inthat the program modules, and thus also the programs assembled fromthem, satisfy customary safety standards, in particular the standardsIEC61508 and/or EN
 61496. 11. A sensor/machine interface in accordancewith claim 1, characterized in that a plurality of sensor inputs (5),sensor outputs (7), machine outputs (8) and/or machine inputs (6) areprovided.